Technical Field
The present invention concerns a process for the production of a mold core for the one-part production of wind power installation rotor blades, and for the production of a mold core for same.
Description of the Related Art
Wind power installation rotor blades are components which in operation of the installation are heavily loaded, and in respect of which good structural integrity is already an important consideration for that reason. In that respect it has been found in the course of the years that, particularly with rotor blades assembled from a plurality of components, it is possible to see in the region of the joint locations potential structural weak points which can require increased maintenance and repair effort.
Blade molds and also production processes are admittedly known, which already permit a generally satisfactory and reliable structure to be afforded for rotor blades. Nonetheless there is a need to minimize the number of necessary join locations in order to reduce the risks of defects in rotor blades for wind power installations.
A known approach in that respect is one-piece production of wind power installation rotor blades. In that case a mold core and a plurality of mold portions are provided, wherein the mold portions in the assembled mold form a negative model of the rotor blade to be produced. Provided between the mold portions and the mold core is a volume which is filled with the material of the rotor blade, that is essential for the structure. Particularly preferably composite materials are used in that case, for example GFR or CFR materials.
While the external shape of the rotor blade is predetermined by the mold portions themselves the mold core is responsible for defining the internal shape of the rotor blade and at the same time ensuring that the materials which are arranged in layers in the volume between the mold portions and the mold core fit snugly and exactly to the external shape predetermined by the mold portions.
A process for the one-piece production of a wind power installation rotor blade is known for example from T2. The process described there describes the use of a fixed mold core surrounded by an elastic outer layer. By compression of the elastic outer layer in conjunction with the hard core, when the mold portions are assembled the fiber layers are pressed against the mold portions.
The known process suffers from a number of disadvantages. On the one hand the provision of a fixed mold core requires it to be produced with a high degree of precision. That necessitates a high level of manufacturing expenditure for the mold core. In addition, because of the elastic external region of the mold core, there is the danger that, when the mold portions are pressed together, distortion or waviness occurs in the fiber material layers between the mold core and the mold portion, and that overall endangers the structural integrity of the rotor blade. Furthermore the geometry of the rotor blade is limited to comparatively simple geometrical shapes by virtue of the fixed mold core and the production complication and expenditure required for same. A mold core of the kind described in DE 602 107 29 T2 cannot be manufactured with satisfactory quality for aerodynamically optimized rotor blades which possibly have interleaved portions and undercut configurations. Furthermore rigid molded bodies cannot be removed from such rotor blades or can be removed therefrom only with very great difficulty as the rotor blades are joined and hardened in one piece.